I love the mockups from Uri and Ken so here is my best of

Login Screen
- on top you have an panel with time (date), where you are and power, volume, keyboard, network and power with drop-down you can say volume +, shoutdown
- In the center the login stuff. I would like to have symmetric users 3, 5, 7 so last 4 + guest in addition at the username feeld there is an search where you can put your username e.g. for LDAP network
- if there are notifications on bottom music would be the same in my case than you don't have an battery load issue when the screen has updated every view minutes.
- Bottom right the branding AND the user wallpaper (maybe it will pass the porn test)


User Switch and Lock Screen
- is the same than lock screen so if the screen is locked you can login into your account or in another account in addition you can make a new session for your account.
- to have an overview about the running sessions you have them listed in the notification style

Maybe there could be 2 versions? One for an environment with many users (eg ldap) and with emphasis on the login and password field and the default one for small setups, without a login field.

Proposal for an environment with many users:
- Show no avatars. Show only the login field.
- After the user entered her login, show a single larger avatar and the password field. The login field is still available to change it.



I personal don't like the plasma desktop logo in the bottom right. I liked Kver version way better